Basement membrane is the first extracellular matrix produced during development and provides a physical support of a variety of cells. Basement membrane consists of a unique set of proteins which have various biological activities including cell migration, adhesion, differentiation, and growth. We have been studying molecular basis of the expression and function of basement membrane components as well as their receptors. Recombinant DNA techniques have been used to prepare molecular clones for various basement membrane components. The primary structure of most of these components has been determined by cDNA sequencing. We have identified some of regulatory DNA elements of basement membrane genes. Several nuclear protein factors have been identified and characterized. Relationships between the structure and function of the proteins have been studied using synthetic peptides and expressing exogenous genes in a variety of cell cultures.